When his appointment was announced earlier this month, he was praised by former health secretaries Sir Sajid Javid, who called him “brilliant, and Matt Hancock, who described him as a “natural reformer”.

Dominic Cummings, the former chief adviser to Boris Johnson during the pandemic, took a different view, saying the appointment was a sign “the Westminster system is totally determined to resist any change and will continue all the things of the past 20 years that have driven us into crisis”.

Sir Chris has replaced Simon Case, who stepped down after just over four years as cabinet secretary on health grounds. He has been undergoing medical treatment for a neurological condition for the past 18 months.

Case had at times been a controversial figure, facing scrutiny particularly over his role in the Downing Street parties saga and over messages he exchanged with ministers during the pandemic.

Last week, a government source told the BBC that more than 10,000 civil servants’ jobs could be cut as part of Labour’s push for 5% savings across departments.

Headcount in the civil service topped 513,000 this year, a 33% increase on 2016 and the eighth year in a row that the total has risen, according to the Institute for Government, external.

Ministers recognised civil service numbers “have gone up and up, and in reality that is not going to be able to continue,” the source said.